The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Substrate processing systems for performing deposition and/or etching typically include a processing chamber with a pedestal. A substrate such as a semiconductor wafer may be arranged on the pedestal during processing. In atomic layer deposition (ALD) or atomic layer etch (ALE) processes, different gas mixtures may be sequentially introduced into the processing chamber and then evacuated. The process is repeated multiple times to deposit film or to etch the substrate. In some ALD and ALE substrate processing systems, radio frequency (RF) plasma may be used during one or both steps to activate chemical reactions.
A first reactant gas may be supplied to the processing chamber during a first step of an ALD process. After a predetermined period, reactants are removed from the processing chamber. During a second step of the ALD process, a second reactant gas may be supplied to the processing chamber. Plasma may or may not be used during the second step to initiate a chemical reaction. After the second step, the reactants are removed from the processing chamber. The first and second steps are typically repeated multiple times to deposit film.
The process time required to deposit the film or to etch the substrate using ALD or ALE largely depends on how quickly the reactant gases can be supplied and evacuated from the processing chamber. Therefore there is an incentive to quickly supply and evacuate the reactant gases to reduce process times. However, if the reactant gases overlap in the gas supply lines, undesirable reactions may occur between the reactant gases, which may cause substrate defects. A sticky reactant gas or an insufficient amount of time between different reactant gases may cause overlap of the reactant gases in the gas lines.
Currently, temporal separation and high flow rates are used. Switching of the gases on and off with high pressures may introduce pressure transients into the gas lines and/or in downstream gas distribution devices, which may cause additional substrate defects.